Bile Acid Malabsorption
- Bile acid malabsorption occurs when increased primary bile acids in the colon lead to chronic diarrhea and abdominal symptoms such as discomfort and bloating.
- Definitions (1)
- Type 1: Secondary to ileal dysfunction (e.g., Crohn disease, ileal resection, or radiation injury)
- Type 2: Idiopathic
- Type 3: Secondary to GI disorders other than ileal dysfunction (e.g., chronic pancreatitis, postcholecystectomy, celiac disease, bacterial overgrowth, and others)
- Type 4: Increased bile acid synthesis induced by metformin (does not cause malabsorption but can cause similar symptoms to bile acid malabsorption due to effects of increased bile acid levels in colon)
- Overall prevalence is estimated to be approximately 1% in Western countries (1).
- Among patients with Crohn disease, with ileal resection, prevalence may be as high as 90% (1).
- Among patients with functional diarrhea or diarrhea-predominant irritable bowel syndrome (IBS-D), ~30–40% shown to have dysregulation bile acid synthesis (1)
- Bile acid malabsorption has been observed in up to 43% of patients with microscopic colitis, although data is conflicting and this was not replicated in other studies (1).
- Prevalence of type 3 and type 4 bile acid malabsorption unknown (1)
Etiology and Pathophysiology
- Primary bile acids are synthesized from cholesterol in the liver and secreted in bile after storage in the gallbladder, where they emulsify fats and play a role in micelle formation (1),(2),(3).
- ~95% of bile acids are actively absorbed in the terminal ileum via the apical sodium bile acid transporter (2).
- In the colon, secondary bile acids are formed by modification of primary bile acids by intestinal bacteria; these modifications increase passive absorption of secondary bile acids in the colon. Ultimately, a small amount of bile acids is passively reabsorbed in the colon (3).
- After reabsorption in the ileum or colon, primary and secondary bile acids return to the liver via the portal vein for reuse (2).
- Bile acid malabsorption in the ileum leads to increased levels of bile acids in the colon. There, the bile acids cause diarrhea via multiple mechanisms: stimulation of water, electrolyte, and mucus secretion; stimulation of colonic motility; alterations to microbiome (1).
Genetic variants in proteins involved in enterohepatic circulation of bile acids may contribute to bile acid malabsorption in murine models
- Inflammatory bowel disease (IBD), primarily Crohn disease (ileal resection or ileal disease)
- Radiation therapy associated ileitis (e.g., pelvic radiation therapy)
- Microscopic colitis
No specific measures for prevention
Commonly Associated Conditions
- Crohn disease
- Celiac disease
- Functional diarrhea
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Domino, Frank J., et al., editors. "Bile Acid Malabsorption." 5-Minute Clinical Consult, 27th ed., Wolters Kluwer, 2020. www.unboundmedicine.com/5minute/view/5-Minute-Clinical-Consult/1688908/all/Bile_Acid_Malabsorption.
Bile Acid Malabsorption. In: Domino FJF, Baldor RAR, Golding JJ, et al, eds. 5-Minute Clinical Consult. Wolters Kluwer; 2020. https://www.unboundmedicine.com/5minute/view/5-Minute-Clinical-Consult/1688908/all/Bile_Acid_Malabsorption. Accessed June 2, 2023.
Bile Acid Malabsorption. (2020). In Domino, F. J., Baldor, R. A., Golding, J., & Stephens, M. B. (Eds.), 5-Minute Clinical Consult (27th ed.). Wolters Kluwer. https://www.unboundmedicine.com/5minute/view/5-Minute-Clinical-Consult/1688908/all/Bile_Acid_Malabsorption
Bile Acid Malabsorption [Internet]. In: Domino FJF, Baldor RAR, Golding JJ, Stephens MBM, editors. 5-Minute Clinical Consult. Wolters Kluwer; 2020. [cited 2023 June 02]. Available from: https://www.unboundmedicine.com/5minute/view/5-Minute-Clinical-Consult/1688908/all/Bile_Acid_Malabsorption.
* Article titles in AMA citation format should be in sentence-case
TY - ELEC T1 - Bile Acid Malabsorption ID - 1688908 ED - Domino,Frank J, ED - Baldor,Robert A, ED - Golding,Jeremy, ED - Stephens,Mark B, BT - 5-Minute Clinical Consult, Updating UR - https://www.unboundmedicine.com/5minute/view/5-Minute-Clinical-Consult/1688908/all/Bile_Acid_Malabsorption PB - Wolters Kluwer ET - 27 DB - 5-Minute Clinical Consult DP - Unbound Medicine ER -